Oil-in-water silicone emulsion compositions that through the removal of the water fraction form a water-repellent, stain-resistant, and heat-resistant cured film that exhibits mold releasability and peeling releasability are used in paints, paper coating agents, mold release agents, peeling release agents, fiber treatment agents, cosmetics, and so forth. There has been demand in recent years for an oil-in-water silicone emulsion composition that does not employ a tin catalyst as the curing catalyst, and this has led to the appearance of a composition comprising a hydroxyl-containing diorganosiloxane, a silicone resin, and an aminoxy group-terminated diorganosiloxane (refer to JP 06-073291 A) and a composition provided by the mixing and subsequent emulsification of a hydroxyl-containing diorganosiloxane and, as a crosslinking agent, a compound selected from linear siloxanes that have the aminoxy group in side chain position, cyclic aminoxysiloxanes, aminoxysilanes, and the partial hydrolysis products of the preceding (refer to JP 11-193349 A). However, these compositions have had the problems of an inadequate strength on the part of the cured film and/or an inadequate adherence to substrate by the cured film.
Oil-in-water silicone emulsion compositions that contain colloidal silica have been introduced in order to solve these problems (refer to JP 56-016553 A, JP 59-152972 A, JP 09-165554 A, and JP 10-168393 A).
However, based on storage stability considerations, the prior colloidal silica-containing oil-in-water silicone emulsion compositions have contained a polyorganosiloxane whose degree of polymerization has been increased by the emulsion polymerization during emulsion production of octamethylcyclotetrasiloxane and/or decamethylcyclopentasiloxane using a strong acid or strong base as the polymerization catalyst. A problem with these oil-in-water silicone emulsion compositions has been the presence of large amounts of siloxane oligomers, e.g., octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and so forth, in the final product. This problem is due to the simultaneous occurrence of siloxane bond cleavage reactions during the emulsion polymerization with the production of new low molecular weight polyorganosiloxanes. Due to the volatility of siloxane oligomers such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and so forth, these oil-in-water silicone emulsions have had the problem of not being usable depending on the particular application.